Most likely it means there is another instance of siad running. Look at your running processes (task manager). There should be only one siad if the wallet is started. You can try to kill all siad processes and then restart your wallet.

So that's the weird thing....I checked to make sure all applications were closed. Just retried to open it and still getting the same error message. I made sure everything was shut down before trying to open it.

I just deleted the wallet completely and downloaded it again, rebooted my MacBook and after a very long time "Loading Sia..." I am still getting the same problem. Is anyone else having this same problem? I need to get my coins off this wallet......and hold them at the exchange until things improve...but can't access them.